Select Page

Restoring Habitat on the M. Fork John Day

Feb 11, 2015

The Oxbow Conservation Area, located on the Middle Fork John Day River, exhibits critical habitat for Chinook salmon, Steelhead and Bull Trout. Dredge mining severely channelized the riverbed in the 1940s leading to a straightened channel and disconnected floodplain. The Confederated Tribes of Warm Springs teamed up with the Bureau of Reclamation and a variety of other partners to restore two miles of river channel affected by mining. Watch the accomplishments made in 2014 on the third of five phases of restoration to the site.

Why is a meandering stream important?

A meandering and a channelized stream.

A meandering and a channelized stream.

A meandering stream is one that has curves and turns along its length. Streams naturally meander and the meandering process eventually results in a floodplain surrounding the stream channel, except where valley characteristics prevent floodplain formation. Floodplains are desirable because they spread flood energy across a wide area, reduce flood peaks as flood flows spread out, prevent erosion, and provide habitats for streamside vegetation and wildlife. In the graphic above, note the meandering stream with full access to the surrounding floodplain. Since floodplain soils tend to be very fertile, farmers and ranchers often straightened streams to make use of it. Streams were also straightened with the belief that it would control flooding. We now know that the opposite is true. Straightened streams tend to cut deep channels that are cut off from the surrounding floodplain. During flood events, these channels tend to concentrate flood energy in a small area, resulting in increased erosion. Also, the benefits of the stream on the surrounding area are reduced since the stream length is greatly diminished. In the graphic above, note the straightened stream that is trapped in its channel with no access to the surrounding floodplain.